autofs-5.0.6 - reinstate singleton mount probe

From: Ian Kent <ikent@redhat.com>

The change to have the kernel process text based mount options can
introduce lengthy timeout waits when attempting a mount to a host
that is not available.

To avoid these waits autofs should probe singleton mounts if it
thinks mount.nfs will pass text options to the kernel (which of
course implies the kernel supports this).
---

 CHANGELOG            |    1 +
 daemon/automount.c   |    7 +++++++
 include/mounts.h     |    1 +
 modules/replicated.c |   18 ++++++++++++++++--
 4 files changed, 25 insertions(+), 2 deletions(-)


--- autofs-5.0.6.orig/CHANGELOG
+++ autofs-5.0.6/CHANGELOG
@@ -26,6 +26,7 @@
 - ignore duplicate exports in auto.net.
 - add kernel verion check function.
 - add function to check mount.nfs version.
+- reinstate singleton mount probe.
 
 28/06/2011 autofs-5.0.6
 -----------------------
--- autofs-5.0.6.orig/daemon/automount.c
+++ autofs-5.0.6/daemon/automount.c
@@ -51,6 +51,9 @@ const char *libdir = AUTOFS_LIB_DIR;	/*
 const char *mapdir = AUTOFS_MAP_DIR;	/* Location of mount maps */
 const char *confdir = AUTOFS_CONF_DIR;	/* Location of autofs config file */
 
+unsigned int nfs_mount_uses_string_options = 0;
+static struct nfs_mount_vers vers, check = {1, 1, 1};
+
 /* autofs fifo name prefix */
 const char *fifodir = AUTOFS_FIFO_DIR "/autofs.fifo";
 
@@ -1273,6 +1276,8 @@ static int do_hup_signal(struct master *
 	if (status)
 		fatal(status);
 
+	nfs_mount_uses_string_options = check_nfs_mount_version(&vers, &check);
+
 	master_mutex_lock();
 	if (master->reading) {
 		status = pthread_mutex_unlock(&mrc.mutex);
@@ -1936,6 +1941,8 @@ int main(int argc, char *argv[])
 
 	defaults_read_config(0);
 
+	nfs_mount_uses_string_options = check_nfs_mount_version(&vers, &check);
+
 	kpkt_len = get_kpkt_len();
 	timeout = defaults_get_timeout();
 	ghost = defaults_get_browse_mode();
--- autofs-5.0.6.orig/include/mounts.h
+++ autofs-5.0.6/include/mounts.h
@@ -95,6 +95,7 @@ struct nfs_mount_vers {
 	unsigned int fix;
 };
 int check_nfs_mount_version(struct nfs_mount_vers *, struct nfs_mount_vers *);
+extern unsigned int nfs_mount_uses_string_options;
 
 unsigned int query_kproto_ver(void);
 unsigned int get_kver_major(void);
--- autofs-5.0.6.orig/modules/replicated.c
+++ autofs-5.0.6/modules/replicated.c
@@ -901,6 +901,7 @@ int prune_host_list(unsigned logopt, str
 	unsigned int v2_udp_count, v3_udp_count, v4_udp_count;
 	unsigned int max_udp_count, max_tcp_count, max_count;
 	int status;
+	int kern_vers;
 
 	if (!*list)
 		return 0;
@@ -920,9 +921,22 @@ int prune_host_list(unsigned logopt, str
 	 * or a single host entry whose proximity isn't local. If so
 	 * return immediately as we don't want to add probe latency for
 	 * the common case of a single filesystem mount request.
+	 *
+	 * But, if the kernel understands text nfs mount options then
+	 * mount.nfs most likely bypasses its probing and lets the kernel
+	 * do all the work. This can lead to long timeouts for hosts that
+	 * are not available so check the kernel version and mount.nfs
+	 * version and probe singleton mounts if the kernel version is
+	 * greater than 2.6.22 and mount.nfs version is greater than 1.1.1.
 	 */
-	if (!this || !this->next)
-		return 1;
+	if (nfs_mount_uses_string_options &&
+	   (kern_vers = linux_version_code()) > KERNEL_VERSION(2, 6, 22)) {
+		if (!this)
+			return 1;
+	} else {
+		if (!this || !this->next)
+			return 1;
+	}
 
 	proximity = this->proximity;
 	while (this) {